ul {
    list-style: none;
}

a {
    text-decoration: none;
}

#container {
    position: relative;
    width: 500px;
    height: 260px;
    margin: 20px auto;
    overflow: hidden;
    /*溢出隐藏：只显示一张图片*/
}

#container .parent {
    position: absolute;
    width: 2500px;
    /*整个图片层长度：500*5=2500*/
    height: 260px;
}

#container .parent li {
    float: left;
    width: 500px;
    height: 100%;
}

#container .parent li img {
    width: 100%;
    height: 100%;
}

#container .btnLeft,
#container .btnRight {
    width: 30px;
    height: 30px;
    background-color: #9E9E9E;
    border-radius: 20%;
    opacity: 80%;
    position: absolute;
    /*包含块为图片显示层container*/
    top: 0;
    bottom: 0;
    margin: auto;
    font-size: 20px;
    color: #f40;
    text-align: center;
    line-height: 30px;
}

#container .btnLeft {
    left: 10px;
}

#container .btnRight {
    right: 10px;
}

#container .btnLeft:hover,
#container .btnRight:hover {
    opacity: 90%;
    cursor: pointer;
}

/*蒙层*/
#container .modal {
    width: 100%;
    height: 40px;
    background: rgba(0, 0, 0, .3);
    position: absolute;
    left: 0;
    bottom: 0;
    line-height: 40px;
    padding: 0 40px;
    box-sizing: border-box;
}

#container .modal .title {
    float: left;
    color: #fff;
    font-size: 12px;
}

#container .modal .dots {
    float: right;
    position: absolute;
    bottom: 10px;
    left: 340px;
}

#container .modal .dots li {
    width: 15px;
    height: 15px;
    border-radius: 50%;
    float: left;
    margin: 0 5px;
    cursor: pointer;
}

.clearfix::after {
    content: "";
    display: block;
    clear: both;
}

.on {
    background-color: red;
}

.off {
    background-color: gray;
}